An organic light-emitting diode (OLED) display device with self-luminous, low driving voltage, high luminous efficiency, short response time, high definition and contrast, nearly 180° viewing angle, wide temperature range, flexible display and large area with full-color display and many other advantages, which is recognized as the most promising display device by an industry. The OLED display device can be divided into two types: a passive matrix OLED (PMOLED) and an active matrix OLED (AMOLED) according to a driving mode, wherein, AMOLED has a matrix arrangement of a pixel, belonging to the active display type, which is high luminous efficiency, and usually used for a high-definition large-size display device.
At present, in a production process of a flat display panel, a defect such as a brightness mura often occurred due to a production process and the like, appearing a bright or a dark spot, which leads to a decrease of the display quality of the panel. In order to eliminate the defect such as the brightness mura of the OLED display panel, but a compensation table is generally used in the prior art to store a compensation information of each pixel in the OLED display panel. When projecting an image, a driver board looks for the compensation table and adjusts a signal, which the signal in a dark area of the panel is raised and the signal in a bright area is lowered, showing an uniform display effect.
In the compensation table, each pixel corresponds to a set of the compensation information, and each set of the compensation information contains one or more compensation data, for the compensation table of grayscale, the compensation data is an adjustment value of a specific grayscale. In the prior art, a size of the compensation table is generally equal to a number of pixels multiplied by the size of each set of the compensation information, and the compensation table occupies a large amount of a system storage space.
The OLED display panel corresponds to a plurality of different color channels, different grayscale compensation tables. In order to save a cost and reduce a transmission time of a data, the compensation table needs to be compressed and stored first. For the grayscale compensation table, since the compensation data stored in the compensation table is the adjustment value of the specific grayscale, each grayscale compensation table actually corresponds to one image, and the compression of the grayscale compensation table is actually equal to the compression of the image.
Different grayscale compensation table is that there is the plurality of redundancy between images. For the same color channel, the redundancy between the images of different grayscale is particularly remarkable, a texture between the images is very similar. If there is a way to remove the redundancy between the different grayscale images, a compression efficiency of the grayscale compensation table can be greatly improved.
On the other hand, each grayscale compensation table will affect a compensation effect of a certain color channel and a certain grayscale. If there is an insufficient quality of the compensation table on a group of the grayscale compensation tables in the display panel, a panel quality will be affected.
An existing encoder supports an encoding of a color spaces which are 4:0:0, 4:2:2 and 4:4:4, and using of the existing encoders encodes the images, that is, grayscale compensation table, can achieve a purpose of compressing grayscale compensation table. However, a configuration used in the prior art for encoding the grayscale compensation table is all intra, that is, an all-intra coding is performed on each compensation table. When encoding the grayscale compensation table, each compensation table is independent, and there is no relation between the compensation table and the compensation table. When encoding, only an all-intra prediction module is used to reduce an all-intra redundancy. It does not consider the redundancy between different compensation tables. Moreover, when setting a quantization coefficient (QP), only the compression effect of the compensation table is taken as the purpose, and an optimization of an overall purpose is not taken into consideration. In fact, only a set of the compensation table of all the images achieving the quality standard, the quality of the display panel is guaranteed. In short, the defects of a conventional compressing method of the grayscale compensation table of the OLED display panel is that the redundancy between the images is not taken into account when compressing each image; when setting the quantization coefficient (QP), it does not take into account the overall optimum performance of the compression of the plurality of compensation tables.